A microsurgical instrument of this type is known from U.S. Pat. No. 4,258,716. The essential features of such an instrument are the two jaw parts that are rotatable toward one another; depending upon the intended use, they may be embodied as grippers, scissors, clamps or the like. The jaw part of the instrument is also useful for a narrowly restricted, poorly accessible field of operation, because the instrument and the surgeon's hand do not block the surgeon's view.
In the known microsurgical instrument, a helically turned face is provided on the posterior end of the rotating rod, passing through a transverse slit in a sheath that is axially displaceable by the tappet and is guided in a non-twisting manner. The stationary handle part is disposed in an axial extension of the tube, while the actuating handle part extends parallel to it a small angle away and rests, with a lever bent at right angles, toward the rear of the tappet. The actuating handle part is preferably depressed toward the stationary handle part by the surgeon's thumb.
With this manner of actuation, the surgeon must assume a hand position that is not optimal for highly precise guidance of the microsurgical instrument. Above all, the surgeon cannot, with this kind of actuation, exert great force, as is particularly necessary in applications where the microsurgical instrument is used as a scissors for severing relatively solid tissues, such as cartilage in particular. Finally, the surgeon's hand also prevents an unhindered view of the field of the operation when the instrument is actuated in this way.
In the known instrument, the lever arm of the actuating handle part engages the guide tube of the tappet through a longitudinal slit in order to be able to displace the tappet axially. The guide tube of the tappet is thus open in parts, and pieces of tissue, blood or dirt can get into the guide tube. This makes the cleaning and sterilizing of the instrument difficult and labor-intensive. Finally, the known instrument is extremely complicated in structure and thus expensive to manufacture.